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src/hotspot/share/oops/instanceRefKlass.cpp
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rev 50107 : [mq]: pp2_work
@@ -1,7 +1,7 @@
/*
- * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
@@ -28,14 +28,12 @@
#include "oops/instanceRefKlass.inline.hpp"
#include "oops/oop.inline.hpp"
void InstanceRefKlass::update_nonstatic_oop_maps(Klass* k) {
// Clear the nonstatic oop-map entries corresponding to referent
- // and nextPending field. They are treated specially by the
+ // and discovered fields. They are treated specially by the
// garbage collector.
- // The discovered field is used only by the garbage collector
- // and is also treated specially.
InstanceKlass* ik = InstanceKlass::cast(k);
// Check that we have the right class
debug_only(static bool first_time = true);
assert(k == SystemDictionary::Reference_klass() && first_time,
@@ -43,26 +41,37 @@
debug_only(first_time = false);
assert(ik->nonstatic_oop_map_count() == 1, "just checking");
OopMapBlock* map = ik->start_of_nonstatic_oop_maps();
- // Check that the current map is (2,4) - currently points at field with
- // offset 2 (words) and has 4 map entries.
- debug_only(int offset = java_lang_ref_Reference::referent_offset);
- debug_only(unsigned int count = ((java_lang_ref_Reference::discovered_offset -
- java_lang_ref_Reference::referent_offset)/heapOopSize) + 1);
+#ifdef ASSERT
+ // Verify fields are in the expected places.
+ int referent_offset = java_lang_ref_Reference::referent_offset;
+ int queue_offset = java_lang_ref_Reference::queue_offset;
+ int next_offset = java_lang_ref_Reference::next_offset;
+ int discovered_offset = java_lang_ref_Reference::discovered_offset;
+ assert(referent_offset < queue_offset, "just checking");
+ assert(queue_offset < next_offset, "just checking");
+ assert(next_offset < discovered_offset, "just checking");
+ const unsigned int count =
+ 1 + ((discovered_offset - referent_offset) / heapOopSize);
+ assert(count == 4, "just checking");
+#endif // ASSERT
+
+ // Updated map starts at "queue", covers "queue" and "next".
+ const int new_offset = java_lang_ref_Reference::queue_offset;
+ const unsigned int new_count = 2; // queue and next
+ // Verify existing map is as expected, and update if needed.
if (UseSharedSpaces) {
- assert(map->offset() == java_lang_ref_Reference::queue_offset &&
- map->count() == 1, "just checking");
+ assert(map->offset() == new_offset, "just checking");
+ assert(map->count() == new_count, "just checking");
} else {
- assert(map->offset() == offset && map->count() == count,
- "just checking");
-
- // Update map to (3,1) - point to offset of 3 (words) with 1 map entry.
- map->set_offset(java_lang_ref_Reference::queue_offset);
- map->set_count(1);
+ assert(map->offset() == referent_offset, "just checking");
+ assert(map->count() == count, "just checking");
+ map->set_offset(new_offset);
+ map->set_count(new_count);
}
}
// Verification
@@ -72,11 +81,11 @@
// Verify referent field
oop referent = java_lang_ref_Reference::referent(obj);
if (referent != NULL) {
guarantee(oopDesc::is_oop(referent), "referent field heap failed");
}
- // Verify next field
+ // Additional verification for next field, which must be a Reference or null
oop next = java_lang_ref_Reference::next(obj);
if (next != NULL) {
guarantee(oopDesc::is_oop(next), "next field should be an oop");
guarantee(next->is_instance(), "next field should be an instance");
guarantee(InstanceKlass::cast(next->klass())->is_reference_instance_klass(), "next field verify failed");
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